As US regulators work toward lowering arsenic levels in drinking water, a new study from Taiwan shows that levels currently considered "acceptable" can increase cancer risk.

Earlier this year, the US Environmental Protection Agency (EPA) issued a ruling that called for maximum allowable arsenic levels to be lowered from 50 parts per billion (ppb) to 10 ppb in an effort to cut the health risks associated with the contaminant.

Now researchers report that arsenic levels between 10 ppb and 50 ppb in drinking water increase a person's risk for developing bladder cancer.

The risk of urinary cancer increased as exposure to arsenic increased, the investigators found.

Exposure to arsenic levels between 10.1 ppb to 50 ppb in drinking water nearly doubled cancer risk compared to the risk in the general population.

Risk was roughly 8 times higher when levels were between 50 ppb and 100 ppb and 15 times higher for people exposed to arsenic levels exceeding 100 ppb.

The new findings make an important contribution to improving the precision of the estimated risk of cancer of the urinary tract associated with ingested arsenic from drinking water," Dr. Kenneth P. Cantor of the National Cancer Institute in Bethesda, Maryland, said in a commentary on the study.

Arsenic is found naturally in rocks, soil, water and air. Industrial, agricultural or mining operations can also cause arsenic contamination in the surrounding environment.

Scientists say that most water sources in the United States contain less than 5 ppb of arsenic, but "there may be hot spots with...higher than the predicted occurrence.

More water systems in the western states that depend on underground sources of drinking water have naturally occurring levels of arsenic at levels greater than 10 ppb than in other parts of the US. Parts of the Midwest and New England have systems whose current arsenic levels range from 2 to 10 ppb.

American Journal of Epidemiology March 1, 2001;153:411-418

Dr. Mercola's Comments:

Most of us will benefit from drinking one quart of water for every fifty pounds of body weight and eliminating all other fluids. This is one of the most important aspects of following the diet program. This study could not have come at a better time, as the US Environmental Protection Agency is now saying that it will do away with recently imposed reductions in the amount of arsenic allowed in the drinking water. The upper limit had been 50 ppb (parts per billion) for over 50 years, but scientists have been calling for a reduction of that level for a long time. Most European countries have lowered the allowable levels dramatically. Finally heeding the call of the scientific community, the upper limit had recently been adjusted to 10 ppb. Actually, many researchers and environmentalists had been asking for a limit of 5 ppb. Now the government says it needs more time to investigate and look at the evidence. For more information on this story see the articles written in the New York Times . Unfortunately, in addition to arsenic from industrial contamination and naturally occurring arsenic, it is also being added intentionally to any water supplies that are fluoridated, as arsenic is a common contaminant of the chemicals used in the fluoridation process (1, 2). Related Articles: Arsenic Triggers Flood Of Free Radicals EPA's Proposed Arsenic Reduction May Stop Water Fluoridation Spirulina for Arsenic Poisoning Too Much Arsenic in Water?